<template>
    <div>
        <div class="box" @click="changeRect" ref="box"></div>
    </div>
</template>

<script>
export default {
    methods:{
        changeRect(){
          this.$refs.box.style.borderRadius="50%"
          this.$refs.box.style.backgroundColor="springgreen"
       
        }
    }
}
</script>

<style lang="scss">
    .box{
        width: 100px;
        height: 100px;
        border:1px solid #000
    }
</style>